The invention relates to axial flow rotary separators of the type which may be used in a combine harvester and particularly to an improved straw discharge arrangement for the downstream end of a cylindrical housing of such a separator.
The general mode of operation of such separators is well known. A rotor having an upstream threshing and a downstream separating portion extends axially through a generally cylindrical housing having a threshing gate or concave upstream and a suitably foraminous downstream separating portion, the rotor and housing cooperating as the rotor rotates to propel crop material received from a suitable upstream feeding device in an annular space between them generally downstream in a helical path while processing the material so that a portion of it is expelled through the threshing grate and foramina of the separator housing while the remainder, including straw, is discharged from within the downstream end of the separator housing.
It is generally desirable to control the straw discharge, at least to some degree, and typically to direct it downwards towards the ground. However, any interference with the free flow of material at the outlet end of the annular space may result in congestion with consequent increase or power consumption for the separator and reduction of separating capacity at the downstream end of the separator. A separator of the general type described above and a particular means for dealing with the straw discharge is disclosed in U.S. Pat. No. 3,863,643, DePauw. However, the method there disclosed has the disadvantage of requiring additional space as well as the cost of constructing the bulky "expansion chamber". Other known separator housing discharge treatments, for example those using transverse beaters, also incur penalties in increasing overall power consumption and sacrificing compactness for the benefit of achieving a particular material handling result.